Composites of Etheric Phosphazenes and metal oxides have been proposed in copending and coassigned U.S. Pat. No. 5,010,128--Coltrain et al filed Mar. 27, 1989. The formation of films of the composite materials, possibly with antistatic properties, is proposed in Coltrain et al.
Phosphazene polymers have also been suggested for use where higher temperature polymers are desirable such as in gaskets for engines, in friction surfaces, and as membranes for separations of gases or liquids. Such uses would not require the addition of salt as the gasket, or friction materials would not need to be conductive or have antistatic properties. In use as a gasket material, membranes, or friction surface, as well as in polymer film antistatic surface coats, it is advantageous that the polymer has good abrasion resistance, hardness, and strength. Therefore, it would be desirable if these properties could be improved for phosphazene polymers.
It has been disclosed in U.S. Pat. No. 4,218,556--Hergenrother et al that chlorosphosphazene polymers can be cross-linked with tetraalkylorthosilicate. Great Britain Patent 1,052,388--Emblem et al discloses that phosphazene trimeric materials may be cross-linked with similar silicates. However, these cross-linked materials have the disadvantage that they are difficult and expensive to make and are not believed to be abrasion-resistant or tough. U.S. Pat. No. 4,026,839--Dieck et al discloses polyphosphazene polymer and silicone rubber blends that are fire retardant and may form foams. U.S. Pat. No. 4,6668,762--Ogata and U.S. Pat. No. 3,304,270--Dickerson also disclose silicon phosphorus containing polymer compositions. It has been disclosed in Exarhos et al, ".sup.31 P NMR Studies of Aqueous Colloidal Dispersions Stabilized by Polyphosphazene Adsorption", J. Am. Ceram. Soc., 71 (9) C-406-C-407 (1988), and Exarhos et al "Molecular Spectroscopic Characterization of Binding Interactions in Phosphazene Stabilized Alumina Dispersions", October 1987, presented at the Materials Research Society 23rd University Conference on Ceramic Science held in Seattle, Wash., Aug. 31, 1987, that polyphosphazenes can be utilized to stabilize alumina dispersions. In the process disclosed in the Exarhos et al articles, a small amount of polyphosphazene is mixed with a large amount of large (0.4 micron diameter) aluminum particles. The purpose of the Exarhos et al processing is to form densified ceramic materials by utilizing polyphosphazene as a binder.
There remains a need for phosphazene polymer fibers that have improved properties of cost, ease of formation, strength, and toughness. Flame-retardant behavior, biocompatibility, transparency, and dissipation of static charge in phosphazene fiber materials also is desirable.
Polyphosphazene antistatic compositions recently have been proposed in copending and coassigned application Ser. No. 087,480 filed Aug. 20, 1987, by Chen et al. In the copending application polyphosphazene is combined with a salt in order to form a conductive composition. This composition has been suggested for use in photographic antistatic layers. While a satisfactory antistatic composition, the material is somewhat tacky and not altogether suitable as an outer coating. Cyclic phosphazenes have also been disclosed for antistatic layers in Japanese Application 129882--Konishiroku published Dec. 11, 1987.